A 2',4'-Bridged Nucleic Acid Containing 2-Pyridone as a Nucleobase: Efficient Recognition of a C´G Interruption by Triplex Formation with a Pyrimidine Motif

Satoshi Obika, et al.
Triplex formation between duplex DNA and a triplex-forming oligonucleotide (TFO) has been noted in practical applications of antigene methodology and in genomic analysis. In the triplex DNA formed with the pyrimidine motif, the homopyrimidine TFO binds to the homopurine tract of the target duplex DNA in a sequence-specific manner through the formation of Hoogsteen hydrogen bonds to form T´A´T and C‡ ´G´C triads. Interruption of the homopurine sequence of the target duplex DNA by a pyrimidine nucleotide causes destabilization of the triplex. Chemical modification of the TFOs in the nucleobase moiety has been reported to give efficient recognition of a pyrimidine ´ purine base pair, such as a C´G or T´A base pair.[1, 2] However, development of practical TFOs for recognition of general duplex DNA sequences is still pending.